The present invention relates to a hub bearing assembly for a driven wheel of a motor vehicle wherein the drive shaft, hub and wheel are non-rotatably connected together and wherein the drive shaft terminates in a joint which supports the inner ring of the bearing assembly and which is provided on the free front side with a front gear tooth arrangement which engages with the mating front gear tooth arrangement of the wheel fastened on the outer part of the coupling by means of a nut or the like threaded into a bore.
U.S. Pat. No. 2,906,558 shows a bearing arrangement generally of the above type. In this prior known construction, the shaft terminates in a joint, the outer part of which serves as a hub for a double row rolling bearing assembly. The free front side is provided with a radially centering front gear tooth arrangement which engages with a mating counter gear tooth arrangement of the wheel. The inner race ring for one row of the double row bearing is directly machined in the outer peripheral surface of the outer part of the joint. Additionally it has a bearing surface for a bearing race which carries the second inner race ring of the rolling bearing assembly as well as a threaded section to receive a nut for axial fastening and adjustment of the bearing race. Another nut threaded in an internal thread of the outer part of the joint pushes the wheel into the front gear tooth arrangement of the outer part of the joint.
A drawback in this known prior assembly is the fact that the outer part of the joint has an extremely complicated outer surface configuration comprising a plurality of different sections such as the race, bearing surface and thread section which are somewhat expensive to fabricate. Furthermore, an additional nut is required for axial fastening and adjustment of the bearing. Moreover, the nut required for fastening the wheel to the outer part of the joint extends substantially in a radially outward direction and has several ears for engagement by a tool or the like to thread or actuate the nut. These projections or ears increase the risk of damage.
With the foregoing in mind, it is an object of the present invention to provide an improved hub bearing assembly of the above type characterized by novel features of construction arrangement wherein the individual parts and especially the outer part of the joint are configured of a simple shape which can be easily manufactured and additionally the number of individual parts, particularly those necessary for connecting and fastening the wheel bearing unit are reduced considerably. To this end, in accordance with the present invention, the rolling bearing which is a separate unit from the outer part of the joint is supported between two shoulders of the outer joint part and the wheel flange carrying the wheel and the wheel flange has a threaded central bore having a thread pitch differing from the threads in the bore of the outer sleeve member of the joint. An externally threaded bolt with differential threads or the like threads into the aligned bores of the outer part of the joint and the wheel flange to axially adjust the outer part of the joint, the wheel flange, and the rolling bearing mounted therebetween.
By this construction, the outer peripheral surface of the sleeve member of the joint merely has to be provided with the bearing seat of the rolling bearing which can be easily and economically machined. Furthermore, only a single bolt element is needed for connecting and fastening the parts and for preloading or adjusting the rolling bearing. In accordance with the present invention, and specifically by reason of the differential thread arrangement in the bore of the wheel flange and the sleeve member of the joint and the bolt member, the bearing is simultaneously preloaded or braced in an axial direction and therefore adjusted by the thread of the bolt which also simultaneously non-rotatably connects the wheel rim with the outer sleeve member of the joint by means of interengaging meshing gear teeth of the wheel rim flange and sleeve member respectively. By this arrangement, the rolling bearing does not require any additional fastening elements.
In accordance with another feature of the present invention, the threaded bolt member may be formed with a radially outwardly directed circumferentially extending flange defining a centering surface for the wheel and/or a brake disc. By this arrangement, the wheel may be loosened at any time without affecting the connection of the other parts.
In accordance with still another feature of the present invention, the threaded bolt is provided with a central bore having a multi-faceted planar surface configuration defining a keyway for engagement of a fastening key. By this arrangement, the threaded bolt only has a slight extension so that the damage hazard is additionally reduced as a result of the interiorly located engagement surface for the fastening tool.